xtensa: reorganize SR referencing

- reference SRs by names where possible, not by numbers;
- get rid of __stringify around SR names where possible;
- remove unneeded SR names from asm/regs.h;
- add SREG_ prefix to remaining SR names;

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/include/asm/delay.h b/arch/xtensa/include/asm/delay.h
index e1d8c9e..58c0a4f 100644
--- a/arch/xtensa/include/asm/delay.h
+++ b/arch/xtensa/include/asm/delay.h
@@ -27,7 +27,7 @@
 static __inline__ u32 xtensa_get_ccount(void)
 {
 	u32 ccount;
-	asm volatile ("rsr %0, 234; # CCOUNT\n" : "=r" (ccount));
+	asm volatile ("rsr %0, ccount\n" : "=r" (ccount));
 	return ccount;
 }